bpo-35461: Document C API functions which suppress exceptions. (GH-11119)
diff --git a/Doc/c-api/codec.rst b/Doc/c-api/codec.rst
index dfe3d43..c55f199 100644
--- a/Doc/c-api/codec.rst
+++ b/Doc/c-api/codec.rst
@@ -13,7 +13,7 @@
.. c:function:: int PyCodec_KnownEncoding(const char *encoding)
Return ``1`` or ``0`` depending on whether there is a registered codec for
- the given *encoding*.
+ the given *encoding*. This function always succeeds.
.. c:function:: PyObject* PyCodec_Encode(PyObject *object, const char *encoding, const char *errors)